Szucs, D. 1 , White, S. 2 & Soltesz, F. 1
1 Department of Experimental Psychology, University of Cambridge, Cambridge, UK
2 Queensland University of Technology, Brisbane, Australia
Learning symbolic Arabic digits in early childhood requires the integration of both magnitude and spatial information with symbolic number notation. In two studies we investigated this integration process in detail during the first three years of primary school in 6, 7 and 8 year-old normally developing children. Study 1 used event-related brain potentials to determine the speed of access to magnitude information from Arabic digits in a situation when number meaning was not relevant; in the physical size judgment task of the numerical Stroop paradigm. ERPs provided a practically real-time index of the speed of access to magnitude information uncontaminated by response organization processes. This speed characterized the strength of association between magnitude information and symbolic digits. All age groups accessed magnitude information with similar speed. This suggests that access to basic magnitude information was mature very early during schooling. Study 2 took a step further and examined not only automatic access to magnitude but also automatic access to spatial information from symbolic digits within the same sample of children. Previous research has separately investigated the development of these components. However, developmental trajectories of symbolic number knowledge cannot be fully understood when considering components in isolation. Hence, we integrated these lines of research. The physical judgment task of the numerical Stroop paradigm demonstrated that automatic access to magnitude was present from Year 1 and an automatically evoked distance effect signaled that a refined processing of numerical information had developed. Additionally, a parity judgment task where number meaning was again, irrelevant, showed that the onset of the Spatial-Numerical Association of Response Codes (SNARC) effect occurs from 8 years of age (Year 2 of school). These findings uncover the developmental timeline of the integration of magnitude and spatial information during the early learning of Arabic digits in normally developing children.